The goal of this research is to more clearly define the cardiac responses to acute uremia. We will extend our previous studies to more completely define the cardiac response in the rat with acute uremia, to continue studies on the effects of uremia on a longer term basis on cardiac function, to attempt to uncover subcellular mechanisms that might explain abnormal cardiac responses, to study protein synthesis in the hearts of uremic rats and to investigate the effects of uremia and hemodialysis on myocardial contractility in humans. During the coming year we will continue to focus upon a chronic uremic preparation. We will continue to investigate intracellular and extracellular distribution of ions as they are altered in uremia. Incorporation of triated phenylalanine into myosin will be measured in the intact animal. In vivo studies will be conducted with double labelled amino acids to investigate myosin turnover. Echocardiographic studies will be concluded in humans before and after hemodialysis. Cardiac mechanics will be defined in a new modified working rat heart apparatus. These investigations hopefully will provide insights into new approaches to protecting the hearts of patients with chronic renal disease.